1. Field of the Invention
This invention relates to a tone source circuit for electronic musical instruments which permits the selection of a desired one of a plurality of waveshapes of different duty ratios and is suitable for fabrication as an integrated circuit.
2. Description of the Prior Art
For simultaneously obtaining a plurality of feet ratios, for example, 4', 8' and 16' with a tone source circuit of conventional electronic musical instruments, not only a keyboard circuit requires complicated link wiring but also multi-pole key switches are necessary, resulting in the manufacture becoming troublesome and hence costly. Further, since a variety of tones are usually formed with one kind of waveshape such as a symmetrical rectangular wave, fidelity of tones of stringed instruments which include many high-frequency components is unsatisfactory in some cases. To avoid this, there has been proposed a method of obtaining tones of stringed instruments by making stairstep waves, but this method has the defect of complicated circuit construction including resistors, a mixing circuit, etc.